There are more than one new routes being considered. Mexico is studying one that would off load the containers onto a train, move them by train to the other coast, then reload them onto another container ship. But those ships are huge and carry lots and lots of containers. Seems like unloading and reloading would eat up all of the benefits.
I would think complete automation at both ports would make that process quite efficient. This would be especially so if the overland routes could be improved to the southern border.
That would maximize how much organized crime could steal along the way. LOL.